Various technologies have been used to detect a touch input on a display area. The most popular technologies today include capacitive and resistive touch detection technology. Using resistive touch technology, often a glass panel is coated with multiple conductive layers that register touches when physical pressure is applied to the layers to force the layers to make physical contact. Using capacitive touch technology, often a glass panel is coated with material that can hold an electrical charge sensitive to a human finger. By detecting the change in the electrical charge due to a touch, a touch location can be detected. However, with resistive and capacitive touch detection technologies, the glass screen is required to be coated with a material that reduces the clarity of the glass screen. Additionally, because the entire glass screen is required to be coated with a material, manufacturing and component costs can become prohibitively expensive as larger screens are desired.
Another type of touch detection technology includes bending wave technology. One example includes the ELO Touch Systems Acoustic Pulse Recognition, commonly called APR, manufactured by ELO Touch Systems of Menlo Park, Calif. The APR system includes transducers attached to the edges of a touchscreen glass that pick up the sound emitted on the glass due to a touch. However, the surface glass may pick up other external sounds and vibrations that reduce the accuracy and effectiveness of the APR system to efficiently detect a touch input. Another example includes the Surface Acoustic Wave-based technology, commonly called SAW, such as the ELO IntelliTouch Plus(™) of ELO Touch Systems. The SAW technology sends ultrasonic waves in a guided pattern using reflectors on the surface of the touch screen to detect a touch. However, sending the ultrasonic waves in the guided pattern increases costs and may be difficult to achieve. Additionally, because SAW must propagate on the surface, SAW transmitters and receivers are typically mounted on the same surface where a touch input is to be received. Detecting additional types of inputs, such as multi-touch inputs, may not be possible or may be difficult using SAW or APR technology.
However, due to precision limits of the human finger, a stylus with a narrower tip may be utilized to provide a more precise touch input. It is desirable to be able to distinguish a stylus input from a human finger touch input to be able to provide stylus related functionality. For example, it is desirable to distinguish between a finger input vs. a stylus input. Technologies such as SAW may be unable to distinguish between a finger and a stylus interacting with the guided pattern of the surface acoustic wave. Although a different specialized hardware may be utilized to detect stylus input as compared to hardware utilized to detect human finger input to distinguish the different types of touch inputs, the added cost of including different hardware for different types of touch input detection may be cost prohibitive.